In the modern retail setting, the use of technology to strengthen customer relationships and improve the customer experience, as well as make the day-to-day operations easier for merchants, is of ever-increasing importance. Lighting is one of the technology factors important in creating a shopping environment and experience: one that attracts shoppers, pulls them in, and creates a store personality while reflecting brand and identity. Well-designed retail lighting does not come in a one-size-fits-all package. It is a strategic blend of color, contrast, control, and energy efficiency. As lighting technology brings with it a multitude of opportunities and flexibility in color, effect and light intensity, the lighting design strategy in retail stores may evolve in line with the shopper-driven innovative culture of retail opportunities, and become aligned to various emotional and environmental contexts.
In general, retail lighting comprises two different types of lighting that can be considered as functionally opposite to each other. On one hand, it is concentrated accent lighting, and on the other, diffuse ambient lighting. Both have their applications in store lighting design—to enhance mood or atmosphere, or to focus attention on certain details and merchandise. The human eye reacts differently to variations in color, brightness, and the contrasts between them. As is known in the lighting arts, both accent and ambient lighting can be spectrally tuned using CCT (correlated color temperature) variations and RGB (red, green, blue) color-mixing technologies to affect in-store consumer behavior in a certain way. Dynamic control of RGB lighting can produce seamless changes in brightness and hue to create natural feelings of well-being. Moreover, with flexible settings, light can be adapted to different needs and moods, enhancing customers' shopping experience with ease.
While a variety of general lighting schemes are known and available, presently no dynamic “white light illumination” solution exists for mainstream retail display applications. Retail product packaging designers rely on the static white spectrum of ambient lighting fixtures and create color appearances solely by use of dyes and pigments in the packaging graphics. In general, much of the commercial use of dynamic color is highly theatrical in nature.
When one considers lighting schemes and effects, in particular color-tunable lighting schemes, it is important to have a basic understanding of color and color space. The CIE xy color space diagram, such as illustrated in FIG. 1A, is designed such that the curved horseshoe-shaped boundary corresponds to monochromatic light (ranging from blue to red). The straight edge at the bottom of the CIE xy diagram demonstrates the various shades of purple that can be formed by mixing blue and red, but does not represent any single wavelength of monochromatic light. See, e.g., Wyszecki & Stiles, Color Science, Concepts and Methods, Quantitative Data and Formulae, 2nd Ed., Wiley 2000, Chapter 3.
Similar to the situation of mixing red and blue to get shades of purple, all colors on the interior of the CIE xy diagram are formed by mixing monochromatic wavelengths. This can be done either by mixing multiple monochromatic wavelengths of different colors (e.g. mixing blue and yellow to get white) or by sufficiently broadening the spectrum of illumination (which is essentially mixing monochromatic wavelengths that are spectrally adjacent to each other).
The CIE xy diagram is constructed in such a way that the mixing of any two colors will generate other colors that lie along a straight line connecting those two original colors. In the case of LED lighting, this can be demonstrated by independently powering, for example, a red LED and a green LED, such that decreasing the power on (dimming) one LED will alter the ratio of green photons to red photons, with the result of enabling the color perception of various shades of yellow and orange (even though no photons of “yellow” or “orange” wavelengths are present).
When three LED colors are independently powered (and optically mixed), all colors within the triangle formed by connecting those color points are possible. This is referred to as the “color gamut”. A common example is the modern television or computer display, both of which are typically constructed such that each pixel contains three independently powered red, green and blue lighting elements. Powering all three colors together creates a perception of white. “Off-white”, i.e. slightly color-tinted shades of white, can be generated by slightly changing the balance of red, green and blue color components.